National Coral Reef Monitoring Program
Climate Monitoring Brief: Dry Tortugas National Park
New Subsurface Temperature Recorder deployed at White Shoal in Dry Tortugas National Park
Atlantic Oceanographic & Meteorological Laboratory Coral Program
University of Miami Cooperative Institute of Marine and Atmospheric
Science
National Oceanic Atmospheric Administration
N. Besemer, A. Palacio, M. Jankulak, I. Enochs - October 2024
About this summary brief
The NOAA Atlantic Oceanographic and Meteorological Laboratory (AOML) conducts the long-term National Coral Reef Monitoring Program (NCRMP) to track the status and trends of coral reef ecosystems of the U.S. Atlantic and Caribbean coral reef jurisdictions. This FY21 summary brief provides an overview of the most recent survey efforts.
Expedition summary
The most recent NCRMP Atlantic climate monitoring took place at Dry Tortugas National Park from June 24th to June 29th 2021
Four different sites were visited by 5 team members completing a total of 63 dives.
These sites represent temporal‐resolution monitoring with moored instruments at fixed time‐series which are placed on depth gradient to assess how vertical structure affects reef status and trends.
Data collection
- Subsurface temperature recorders (STRs) were
recovered and redeployed at all 4 study sites (Fig. 1), accounting for
1.1 million temperature observations:
- Pulaski Shoal (1m): 311,609 observations
- White Shoal (5m): 311,213 observations
- Bird Key Reef (15m): 311,560 observations
- Black Coral Rock (25m): 165,695 observations
- At the Bird Key Reef, short term instruments (72h) were deployed to
monitor daily fluctuations in:
- Current: 880 observations
- pH: 879 observations
- Light: 876 observations
- Carbonate Chemistry: 24 samples collected
- Additionally, changes in benthic cover and carbonate production were
monitored at Bird Key Reef by recording:
- Bioerosion: 5 Bioerosion Monitoring Units (BMUs) collected, 10 redeployed
- Calcification: 5 Calcification Accretions Units (CAUs) collected, 5 redeployed
- Benthic cover: 6 landscape mosaics
- Carbonate budget surveys: Benthic cover, sponge, urchin and parrotfish surveys completed at 6 transects
Figure 1: Study sites and depths in Dry Tortugas National Park area
Temperature
Three years of temperature measurements were retrieved and processed from all 4 sites (depths). Temperature was measured using SeaBird Electronics Subsurface Temperature Recorders (STR)s that collected data at 5-minute intervals.
Figure 2: Temperature conditions at four sites in the Dry Tortugas representing a depth gradient: Pulaski Shoal Lighthouse (1m) White Shoal (5m), Bird Key Reef (15m), and Black Coral Rock (25m). Data were collected from June 2021 to XX, with the exception of the 25m STR that recorded until February 7th 2020.
## # A tibble: 83 × 5
## # Groups: MonthYear [27]
## MonthYear Depth MeanT MinT MaxT
## <chr> <fct> <dbl> <dbl> <dbl>
## 1 2021-06 1m 28.2 27.6 28.5
## 2 2021-06 5m 28.5 28.3 28.8
## 3 2021-06 15m 28.4 28.2 28.7
## 4 2021-06 25m 27.8 26.8 28.2
## 5 2021-07 1m 29.2 28.0 30.8
## 6 2021-07 5m 29.4 28.4 30.8
## 7 2021-07 15m 29.2 28.2 30.4
## 8 2021-07 25m 28.6 25.2 29.9
## 9 2021-08 1m 30.2 29.2 31.6
## 10 2021-08 5m 30.3 29.3 31.3
## # ℹ 73 more rows## # A tibble: 48 × 5
## # Groups: Month [12]
## Month Depth MeanT MinT MaxT
## <chr> <fct> <dbl> <dbl> <dbl>
## 1 01 1m 24.2 21.8 25.6
## 2 01 5m 24.1 21.6 25.6
## 3 01 15m 23.5 21.1 25.6
## 4 01 25m 24.3 22.7 25.5
## 5 02 1m 22.7 21.4 24.6
## 6 02 5m 23.0 21.3 24.8
## 7 02 15m 23.9 21.4 25.3
## 8 02 25m 22.9 21.6 24.6
## 9 03 1m 24.9 23.8 26.0
## 10 03 5m 25.1 24.0 26.2
## # ℹ 38 more rowsTemperature values were similar among the 1m, 5m and 15m depths with the lowest temperatures recorded during February 2021 (20.8, 20.7, and 19.9 \(^\circ\)C, respectively) and the the higest temperatures during the summer of 2019 and 2020 (31.7, 31.6, and 31.5 \(^\circ\)C, respectively). Though the 25m STR stopped recording on February 7, 2020, it detected consistent temperature stratification at this site during the summers when it was active. Temperatures at 25m were on average 5-6\(^\circ\)C lower during summer 2018, and 1\(^\circ\)C lower during summer 2019, compared with the values at other depths (Fig. 2).
Diurnal Suite Deployment
At Bird Key Reef additional instruments were deployed for a 72-hour diurnal suite that monitored pH, temperature, light and current speed (Fig. 3). The SeaFET pH logger, EcoPAR and Tiltmeter collected measurements at 5-minute intervals.
Figure 3: Bird Key Reef (15m) diurnal suite monitoring from June 23th to 27th. Top panel: pH and temperature from SeaFET. Bottom panel: Photosynthetically Available Radiation (PAR) and current speed from EcoPAR and Tiltmeter. Grey blocks denote night time throughout sequence of the plot. Instruments measured parameters every 5 minutes.
As part of the diurnal suite, discrete water samples were collected at three-hour intervals (n=24) using Subsurface Automatic Samplers (SAS). These samples will be analyzed for Total Alkalinity (TA), Dissolved Inorganic Carbon (DIC), and Spectrophotometric pH (SpecpH). Using these metrics we can get the calculated values for pCO2 and aragonite saturation state. For more information on SAS vist https://www.coral.noaa.gov/accrete/sas/
Submered Automated Samplers (SAS) deployed to collect water samples every 3 hours
Habitat persistence
Carbonate budget assessments use transect-based surveys to quantify the abundance of carbonate producers, such as corals and crustose coralline algae, as well as carbonate bioeroders, such as grazing parrotfish and sea urchins. Abundances are multiplied by taxon- specific rates of carboante alteration to determine if a reef is in a state of net accretion (habitat growth) or net loss (habitat loss). At East Buoy 3, six transects were established and surveyed in 2015 to obtain carbonate budgets. We revisited this site in 2019 and 2022 to find out the new status of carbonate budget after six years. The transect results showed that carbonate budgets have decreased in 2022. This trend is driven by a reduction in coral cover and calcification as well as a steep increase in parrotfish erosion. MORE SUMMAITON TEXT FOR FGB CARB BUDGETS
Figure 4: Carbonate budgets from East FGB in 2015, 2019 and 2022 and the processes contributing to calcification and bioerosion. The horizontal line in the “Net carbonate production panel” denotes accretionary stasis, the point where the budget flips from habitat grpwth to loss. PF represents parrotfish.
Landscape mosaics are used to quantify the benthic community, and to monitor changes in coral cover over time. Thousands of underwater images are digitally stitched together to create a high-resolution archive of the reef at the time of collection.
Finally, Calcification Accretion Units (CAUs) and Bioerosion Monitoring Units (BMUs) were used to investigate the balance between calcification and erosion. CAUs and BMUs were collected and redeployed for the next sampling cycle. CAUs are processed by the Pacific Climate group and the data will be available within a year. BMUs will be dried and cleaned using a hydrogen peroxide solution. These samples will be weighed and scanned using a CT scanner and then compared to their pre-scans to quantify bioerosion. Data will be available in a year. Please reference previous datasets for more information.
CAU and BMU pair before retreval after being deployed for three years. CAUs are two parallel PVC plates to quantify settled accretors. BMU is mounted coral skeleton installed at the base of the metal stake and has been encrusted.
About the monitoring program
AOML’s climate monitoring is a key part of the National Coral Reef Monitoring Program of NOAA’s Coral Reef Conservation Program (CRCP), providing integrated, consistent, and comparable data across U.S. Managed coral reef ecosystems. CRCP monitoring efforts aim to:
- Document the status of reef species of ecological and economic importance.
- Track and assess changes in reef communities in response to environmental stressors or human activities.
- Evaluate the effectiveness of specific management strategies and identify actions for future and adaptive responses.
Point of Contact
Atlantic Climate team lead: nicole.besemer@noaa.gov
Principal Investigator: ian.enochs@noaa.gov
NCRMP Coordinator: erica.towle@noaa.gov
For more information
Coral Reef Conservation Program: http://coralreef.noaa.gov
NCRMP climate monitoring: https://www.coris.noaa.gov/monitoring/climate.html
NOAA Atlantic Oceanographic and Meteorological Laboratory: http://www.aoml.noaa.gov/
Acknowledgements
These efforts were jointly funded by NOAA’s CRCP and OAP. We would like to thank the National Park Service and Florida Keys National Marine Sanctuary for permitting support and the ANGARI Foundation for field support.
Our Team
Field team members: Anderson Mayfield, Graham Kolodziej, Nicole Besemer, Nathan Formel, Patrick Kiel
Additional lab members involved with NCRMP: Ian Enochs, Benjamin Chomitz, Albert Boyd, Mike Jankulak, Ana Palacio